Post-cardiotomy cardiogenic shock is a significant clinical problem that will effect approximately 1% of all patients undergoing cardiac surgery this year. Experience with mechanical ventricular assistance in these patients at the Brigham and Women's Hospital as well as nationally has been very disappointing, and only approximately 25% of such patients supported with conventional technology will survive to discharge. We are very interested in pursuing the possibility of using genetically modified porcine xenografts to provide temporary cardiac support. Thus far, we have performed transplant surgeries on 11 baboons. Some animals received the heterotopic heart transplant and the others the kidney transplant from the transgenic pig donors to the baboons. The experiments are in progress and the data being generated from those experiments is under continuous evaluation. The initial phase of experiments will address the immunologic questions of graft rejection upon transplantation. These studies will utilize heterotopic transplants attached to an artery and vein in the neck of recipients treated with cyclosporine and leflunomide. Control animals will receive hearts from non-transgenic swine. In a separate experiment we plan to perform a small number of isolated heterotopic kidney grafts obtained from the same transgenic swine cardiac donor as a pilot for possible future research. Early results suggest that modified cardiac xenografts which